Thermostat.



W. BARSTOW.

THERMOSTAT. APPLICATION FILED JUNE 19. 1918.

Patented Feb. 4, 1919.

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wn'ncn BAns'row, or SPOKANE, wAsnme'roN, ASSIGNOR r THOMAS rmnx nvm,

I citizen of the United States, residing at Spofollow'in 0F SEATTLE,WASHINGTON,

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To all whom it may concern:

Be it known that I, WELGH BARs'row', a

'kane, in the county of Spokane and State of Washington, have invented.new and useful Improvements in Thermostats, of which the is a secification.

One 0 ject o the'present invention is to provide in a thermostat abi-metallic couple who'se inertia does not cause it to open or closewhen sub'ected to shock.

- A further 0 ject is to provide a bi-metallic element WhlOh will have alargemovement having regard to its overall dimen- .sions and weight, andwhich will be of great accuracy.

In the accompanying drawing, Figure 1 is a plan view of my improvedthermostat;

Fig. 2 is' a sectional view thereof on the line cated upon the sup apairof metals having the ca 2-2 of Fig. 1 Fig. 3 is a sectional view on theline 3-3 oi Fig. 1.

Referring to the drawing, 1 indicates a suitable base, in which isplvoted a pin 2 having an eccentric head 3-rotatable in a support 4, sothat said support is adjustable on said base by turning the eccentricpin 2.

It is-locked in any desired position by a looking screw 6 screwed intosaid base 1 and passing through a slot 5 in the support 4:.

From said. support extend u wardly a short standard 7 and a lon stan ard8. 0 said standards are secure by screws 9 1n: ner ends of bi-metallicelements 11, 12, each of a general spiral'form, but extending inopposite directions from their fixed ends. The outer ends of saidelements are-secured by ,pins 13, to caps14'having' yoke-shapeentensions 16 in which are ivoted, by p1ns 17,

terminalportions of a ar 18, p1voted,,as

shown at 15, on a standard 20 centrally loort 4. One end of said bar isprovided w1t means, as an aperture 19, for connecting it with a devicefor indicating the extent to which the elements 11, 12, are expanded orcontracted Each bi-metallic element is composed of greatestpractidifierence of heat 'coefliclent of expansion, namely, brass and aproximately 36% nickel steel alloy, the brass aving the greatestcommercially available coefiicient and the alloy the least, inasmuch asit is practically zero, and in some cases negative. The brass and alloyare arranged opposltely 1n the two bi-metallic elements, a brass strip21 belng ar- Speoiflcation of Letters Patent.

Patented Feb. 4, 1919. v Applicaflonflled June 19, 1918. Serial No.240,774.

ranged on the inside, and a strip 22 of alloy on I the outside of thespiral coil 1n one element and the positions be1ng reversed in the otherelement, a strip 23 of alloy being on the inside, and a strip 24 ofbrass being on the outside. Consequently while one element will expand,the other element will contract, with an increase in temperature, andsince their outer ends are pivoted near the opposite ends of the bar 18,which is free to oscillate about its center, the thermostat so composedis statically balanced. Its inertia does not cause it to open or closewhen subjected to shock. 7

Moreover, the two coils linked together, as shown, tend to mutuallyovercome any slight differences of expansion due to hard spots in themetals, or for other reas0ns,:and have therefore only one-half the errorwhich each would have alone.

Another advantage of the present construction is the eater area exposedfor a given crosssectlon of metal, the device thereby responding.quickly to changes in temperature.

I claim 1. A thermostat comprising an oscillatory device andthermostat1c elements, ends of which are secured to portions of saiddevice on opposite sides of its center of oscillation, said elementsbeing arranged, one to 'expand, and the other to contract with anincrease in temperature, said' device bein provided with means forassisting to in icate its movements due to said expansion andcontraction. a

[2. 'A thermostat comprising an oscillatory device and bi-metallicelements each secured fixedly at one end, the other ends of saidelements being secured to ortions of said de- ,vice .on o osite sides 0its center of oscillation, sa1 bi-metallic elements being arranged, theone to expand andthe other to contract, with an increase in temperature,

said device being provided .with means/for vice on opposite sides ofsaid pivot, said hiassisting to; indlcate its movement due to.

metallic elements being arranged, the one to expand, and the other tocontract, with an increase in temperature, said device being providedwith means for assisting to indicate its movement due to said expansionand contraction.

4. A thermostat comprising a device/ar ranged to oscillate about anapproximately central pivot and bi-metall'ic elements each 10 securedfixedly at one end, the other ends of said elements being pivotallysecilred to portions of said device on opposlte sides of said 7 centerof oscillation, the metals of the two elements havin diflerent heatcoeflicients of expansion and eing arranged oppositely in the respectiveelements, saiddevice being provided With means for assisting to indicateits movement due to a change-intemperature.

WELCH BARSTOW.

